Make sure the Setup of the AppBuilder is only done once.

Author: dlemstra

tests/Magick.NET.AvaloniaMediaImaging.Tests/AppBuilderHelper.cs

@@ -0,0 +1,40 @@
+// Copyright Dirk Lemstra https://github.com/dlemstra/Magick.NET.
+// Licensed under the Apache License, Version 2.0.
+
+using System.Threading;
+using Avalonia;
+
+namespace Magick.NET.AvaloniaMediaImaging.Tests
+{
+    internal static class AppBuilderHelper
+    {
+        private static readonly SemaphoreSlim _lock = new(1);
+        private static bool _setupDone;
+
+        public static void Setup()
+        {
+            if (_setupDone)
+                return;
+
+            _lock.Wait();
+
+            try
+            {
+
+                if (_setupDone)
+                    return;
+
+                _setupDone = true;
+
+                AppBuilder
+                    .Configure<Application>()
+                    .UsePlatformDetect()
+                    .SetupWithoutStarting();
+            }
+            finally
+            {
+                _lock.Release();
+            }
+        }
+    }
+}

tests/Magick.NET.AvaloniaMediaImaging.Tests/IMagickImageExtentionsTests/TheToWriteableBitmapMethod.cs

@@ -15,10 +15,7 @@ public class TheToWriteableBitmapMethod
         [Fact]
         public void ShouldReturnWriteableBitmap()
         {
-            AppBuilder
-                .Configure<Application>()
-                .UsePlatformDetect()
-                .SetupWithoutStarting();
+            AppBuilderHelper.Setup();
 
             using var input = new MagickImage(Files.MagickNETIconPNG);
             using var bitmap = input.ToWriteableBitmap();

tests/Magick.NET.AvaloniaMediaImaging.Tests/IMagickImageExtentionsTests/TheToWriteableBitmapWithDensityMethod.cs

@@ -15,10 +15,7 @@ public class TheToWriteableBitmapWithDensityMethod
         [Fact]
         public void ShouldReturnWriteableBitmap()
         {
-            AppBuilder
-                .Configure<Application>()
-                .UsePlatformDetect()
-                .SetupWithoutStarting();
+            AppBuilderHelper.Setup();
 
             using var input = new MagickImage(Files.MagickNETIconPNG);
             input.Density = new Density(150, 300);